Apparatus for heat therapy by inhalation

ABSTRACT

This apparatus incorporates an enclosure (1) designed to contain water in which are immersed two electrodes (9,10) connected to an alternating current source (S). A tube (13) terminating in a nozzle (14) connect the top of this enclosure (1) to a venturi (15) which is connected upstream to the atmosphere and downstream to an inhalation mask (17), so as to form an air/water vapor mixture at a controlled temperature.

The present invention relates to an apparatus for heat therapy byinhalation.

The work of Professor Andre Lwoff has shown that the development of avirus depends on the temperature, which can be characterised in threezones: optimal, infra- and supra-optimal. At supra-optimal temperatures,the viral genetic material is destroyed by the lysozomal enzymes whichare prematurely released, and the development of the virus is blocked.This work forms the subject of a report to the Academie des Sciences deParis (Academy of Sciences of Paris), vol. 291 (8 Dec. 1980) seriesD-957.

On the basis of this work, a Franco-Israeli team of research workers atthe Weizmann and Pasteur Institutes developed a heat therapy ofinfectious coryza and persistent allergic rhinitis. For this purpose, aso-called "rhinotherme" apparatus was designed and formed the subject ofpatent application FR No. 2,399,851. The clinical trials based on thisheat therapy enabled suspension of the symptoms of the disease to beachieved for a long period in a large percentage of the patients,especially in patients suffering from persistent rhinitis which resistedany other treatments.

Although these results are encouraging, the complexity and cost of theapparatus developed for this purpose make this therapy inaccessible tothe general public, so that this simple and wholly natural therapy is,in practice, only used at the very most in the hospital situation. Nowit is clear that an apparatus of simpler design, sold at a reasonableprice, would naturally find its place in any family medicine cabinet inthe same way as electric tooth-brushes or other apparatus for care ofthe gums. Widespread distribution of such an apparatus could havebeneficial effects both on health insurance resources and on the economygenerally, taking account of the frequency of these viral complaintswhich, during some winters, cause the loss of a large number of workingdays.

The object of the present invention is, specifically, an apparatus forheat therapy by inhalation which is simple in design and safe inoperation, the price of which makes it suitable as an apparatus for homeuse.

For this purpose, the present invention has as its subject an apparatusfor heat therapy by inhalation according to claim 1.

The simplicity of this apparatus results from its design, which does notinvolve any moving parts, the motive component consisting either ofsteam under pressure which results from heating water and feeds aventuri, or of the partial vacuum which results from breathing in. Sincethe operating parameters are essentially constant, the temperature ofthe air/steam mixture inhaled can be fixed by the design.

The attached drawing show diagrammatically, and by way of example, twoembodiments and a variant of the apparatus which is the subject of thepresent invention.

FIG. 1 is a sectional view in elevation of one of these embodiments.

FIG. 2 is a partial view of a variant in elevation, partially cut away.

FIG. 3 is a diagram of the second embodiment.

The apparatus illustrated in FIG. 1 incorporates an enclosure 1 formedby a cylindrical container 2 which is closed by a stopper 3 screwed ontothis container. An O-ring sealing gasket 4 situated in a groove 5 madein the side of this stopper 3 serves to effect the sealing between thestopper 3 and the cylindrical container 2.

The wall of the container 2 incorporates an inner stainless steel part 6surrounded by a thermally insulating layer 7 and an external envelope 8which can, for example, be of plastic.

The stopper 3 carries, concentric with its axis of revolution, twocoaxial tubes 9 and 10 made of stainless steel, non-corroding alloy orplatinised titanium, for example. These tubes are connected by twoconductors, 11 and 12 respectively, to an alternating current source S,and have perforations, 9a and 10a respectively, at the top. These tubes,which act as electrodes for heating undistilled water, can obviously bereplaced by two simple rods (not shown) which advantageously terminateat the bottom end in two spheres or discs in order to increase theconducting surface of the electrodes at the bottom of the container, sothat the heating is less dependent on the water level, the waterconstituting both the heating resistance and the product distributed invapour and droplet form.

A tube 13 passes axially through the stopper 3 and terminates in anozzle 14 which extends into the neck of a venturi 15 formed at thejunction between a tube 16, which opens into an inhalation mask 17, anda tube 18 which passes diametrically through the stopper 3 to allow theneck of the venturi 15 to communicate with the atmosphere. A capillarytube 13a connects the bottom of the container 2 to the nozzle 14. Itshould moreover be pointed out that the mask 17 constitutes an example.It could be replaced by two tubes designed to be placed directly in thenozzles and to avoid harming the skin of the face through the effect ofsteam.

The apparatus described operates in the following manner: water ispoured into the container 2 up to a level marked on the inner wall 6 ofthis container, this level being situated at a certain distance, forexample 3 cm, from the lower face of the stopper 3. The stopper 3, withits tubular electrodes 9 and 10, is screwed onto the container 2 and theelectrodes are connected to the alternating current source S. Thepassage of current between these electrodes causes the water to beheated. The openings 9a and 10a enable the water to be maintained at thesame level in the different zones of the container 2, and enables thesteam to be conveyed towards the tube 13 When the water boils afterabout 1 to 2 minutes, the steam produced escapes under pressure throughthe tube 13 and nozzle 14 and creates a partial vacuum in the neck ofthe venturi 15, which draws air in. The adjustment of the venturi iscarried out in such a manner that the mixing of the ambient air at about20° C. and water vapour at 100° C. gives air which is almost saturatedwith water at about 43° C., with a flow rate of the order of 45 l/min.This constant flow rate represents 3/4 litre per second, whichcorresponds to the volume inhaled by an adult individual.

The water vapour reaches the nozzle 14 at a pressure of the order of 10³to 10⁴ Pa. The nozzle 14 has a diameter of 0.5 to 2 mm and the speed ofthe vapour is of the order of 50-200 m/s. The flow rate of the vapour isof the order of 0.33 m³ /h with a density of 0.6 kg/m³. If it is takeninto account that the treatment lasts about half an hour, theconsumption of water is of the order of 1 dl, so that the capacity ofthe enclosure 1 is of the order of 150 cm³.

The air drawn in by the water vapour is ambient air at about 20° C. atthe approximate rate of 2 m³ /h or about 2.6 kg/h. This gives a massflow rate of air saturated with water vapour at 43° C. of 2.8 kg/h. As aresult of the overpressure which exists in the container 2 and thepartial vacuum which exists at the nozzle 14, a certain amount of wateris atomised at the outlet of the tube 13a in the form of droplets from 2to 20 μm in diameter which are intended for deposition on the nasalmucosa and for improving the efficiency of heating of this mucosa, whichhas to be suitably moistened.

The variant illustrated in FIG. 2 incorporates in addition a device formeasuring the temperature, consisting for example of a bimetallic stripthermometer 19 arranged in the inhalation mask 17, the display dial ofthe thermometer being visible to the user during inhalation, whichenables him to ensure that the treatment is progressing correctly.

This measuring device is completed by an adjustment member whichcomprises a ring 20 mounted to rotate around the part of the stopper 3through which the diametral tube 18 passes. This ring 20 has two seriesof openings 21, the diameters of which decrease in the same direction.The openings which have equivalent diameters in each series arediametrically opposed around the ring 20, so that they can be placedsimultaneously opposite the two ends of the diametral tube 18. By meansof this adjustment ring 20, the user can take action in the case wherethe temperature of the atmosphere created inside the inhalation mask 17is incorrect. If this temperature is too high, he will turn the ring 20so as to situate openings 21 of larger diameter at the ends of thediametral tube 18, so that the proportion of air drawn in by the venturi15 will increase and the temperature of the air/water vapour mixturewill decrease. In the opposite case, he will situate openings 21 ofsmaller diameter opposite the diametral tube 18 and the mixturetemperature will increase. In fact, the apparatus will be positivelycalibrated to deliver a mixture at 43° C. starting with air at 20° C.,which represents the commonest case of use. Nevertheless, the measuringand adjustment device enables monitoring to be carried out and thetemperature to be adjusted in the case of operation from otherconditions, when the ambient temperature is different from 20° C., thatof the vapour remaining constant.

According to the invention, the apparatus for heat therapy by inhalationis hence extremely simple, which makes it suitable as an ideal apparatusfor home use, thus taking its place in the family medicine cabinet. Notonly does its simple design enable it to be produced at a reasonableprice, but it requires practically no maintenance apart from elementaryhygiene measures which can consist either in cleaning the mask 17, or inreplacing it after each use or after the series of treatments requiredfor curing one and the same patient.

To heat the water by means of the electrodes described and using theconductivity of the water, it is appropriate to take a tap water theconductivity of which can vary between 1,000 μS/cm and 4,000 μS/cm.

When the conductivity of the water is too low for the area of theelectrodes, it can be increased by adding an acid or NaCl.

In this case, the conductivity of the solution will increaseproportionately with the evaporation of the water, since theconcentration of the solution will increase proportionately with thisevaporation. Given that the electrode area submerged decreases as thelevel of the solution becomes lower, a substantially constant activityis obtained.

The use of tap water does not pose any particular problems in relationto bacteria, since this water is heated to the boiling point to producethe steam required for the apparatus to work properly. The furring whichcan result from the use of hard water can be dissolved by a 10% strengthacetic acid solution. The use of distilled water with added NaCl is ameasure which enables the problem of furring to be eliminated.

By way of example, the dimensioning of the electrodes can be as follows:

assuming a flow rate of air saturated with steam of 0.75 l/s,corresponding to 2.86 kg/h, the mass flow rate of water according to theMollier diagram will be:

    M=0.18 kg/h

the necessary electrical power is ##EQU1## the resistance will have tobe ##EQU2##

Given that, to avoid the effect of electrolysing the water, the currentdensity I/S≦1,200 A/m², ##EQU3##

The calculation of the choice of dimensions should take account of asignificant decrease in the activity from the start of vaporisation, asa result of the presence of bubbles of steam which decrease the usefulwet area of the electrodes.

In addition to modifying the acidity of the water, it is of course alsopossible to act, for example, on the gap between the electrodes.Although the heating system consists advantageously of two electrodesconnected to an alternating current source, which has the advantage ofbeing cheap and of avoiding any accidental overheating by virtue ofthere being no heating in the absence of water, it is however possibleto consider other types of heating, such as heating by the Joule effectwhich consists in immersing an electrical resistance in the enclosure 1in place of the electrodes.

The second embodiment illustrated very schematically in FIG. 3incorporates an enclosure 22 in which a heating element 23 is immersedin the water. This heating element, which can be composed of twoelectrodes and water of low conductivity as in the example describedabove, is connected to a current source S through a compactor comprisinga casing 24 divided into two parts by an elastic membrane 25 bearingmetal cap 26. One of the conductors connecting the current source S tothe heating element 23 passes through the casing 24 and is interruptedbetween two terminals 27. The part of the casing 24 containing theterminals 27 is connected, through a tube 28, to the top of theenclosure 22, while the other part of this same casing 24 communicateswith the atmosphere so that the position of the metal cap 26 relative tothe terminals 27 depends on the pressure difference between theatmosphere and the enclosure 22.

The top of this enclosure 22 is again connected to an inhalation mask 29through a tube 30, along which the flow of the steam produced in theenclosure 22 is controlled by a one-way valve 31. This valve is normallyclosed when the pressure in the tube 30 is equal on the upstream anddownstream sides, and opens when the pressure is higher upstream thandownstream so as to permit the vapour to flow in the direction of theinhalation mask 29. A second valve 32 controls the flow through a tube33 which communicates with the atmosphere and opens into the tube 30downstream from the valve 31. This valve 32 is identical to thepreceding valve so that it likewise opens when the pressure prevailingdownstream of this valve 32 is lower than atmospheric pressure. Eachvalve 31, 32 can be associated with means for adjusting thecross-section of flow in the respective types 30 and 33.

The apparatus according to this embodiment operates in the followingmanner: when the pressure is identical on both sides of the membrane 25,the latter brings the metal cap 26 to bear against the terminals 27,applying voltage to the heating element 23. When the water present inthe enclosure 22 boils and gives off steam, the pressure increasesslightly and the membrane 25 then separates the metal cap 26 from theterminals 27, interrupting the supply to the heating element 23. Theapparatus is then ready for operation.

As soon as a partial vacuum prevails in the downstream part of the tube30 as a result of breathing in from the mask, the valves 31 and 32 opensimultaneously, thereby allowing steam and air to pass through inproportions which depend on their respective cross-sections of flow.

As soon as the pressure in the enclosure 22 is reduced as a result ofthe flow of steam towards the inhalation mask 29, contact between themetal cap 26 and the terminals 27 is re-established and the heating ofthe water releases steam again. As soon as the user stops breathing in,the valves 31 and 32 close again and the production of steam in theenclosure 22 ceases as soon as the pressure slightly exceeds atmosphericpressure. This embodiment differs from the above embodiment essentiallyin respect of the discontinuous mode of operation, the flow of theair/steam mixture only being produced as a result of a partial vacuum inthe tube 30 generated by the user breathing in at the upstream end ofthis tube. The use of two electrodes and of the resistance of the wateras a heating element has the advantage of virtually zero inertia,providing an almost instantaneous response time.

As a variant, it is furthermore possible to eliminate the contactcontrolled by the membrane 25 and to connect the top of the enclosure 22to the atmosphere through a calibrated vent (not shown) designed tomaintain a substantially constant pressure in this enclosure 22, thispressure being chosen to be lower than the pressure at which the valve31 opens.

We claim:
 1. Apparatus for providing heat therapy by inhalation,comprising:wall means defining an enclosure for heating at its boilingtemperature a quantum of aqueous liquid when contained therein to alevel which incompletely fills said enclosure, leaving a headspace ofsaid enclosure unfilled by aqueous liquid above said level; a tubehaving an inlet end and an outlet end, said inlet end of said tubeopening into said headspace of said enclosure and said outlet end ofsaid tube being provided with a nozzle; a pipe secured to said wallmeans and having an inlet end and an outlet end, said inlet end of saidpipe being adapted to be open to the atmosphere, and said outlet end ofsaid pipe including means adapted to provide from said headspace andfrom the atmosphere, in use, a hot, moist air mixture for inhalation bya user for providing heat therapy for the user; said pipe, intermediatesaid inlet and said outlet ends thereof having surface means defining aneck of a venturi therein; said nozzle of said tube opening into saidventuri neck, towards said outlet end of said pipe, so that aspressurized steam issues from said nozzle, atmospheric air will be drawninto said pipe through said inlet end of said pipe and form with saidsteam at said nozzle a hot, moist air mixture; said nozzle and saidventuri neck being dimensioned to provide, in use, a hot moist airmixture having a temperature within the range of 38°-50° C.; and asecond tube secured to said wall means and having an open inlet enddisposed below said level in said enclosure and having an open outletend disposed in said pipe adjacent said nozzle and being adapted tosupply, in use, heated aqueous liquid drawn thereinto from saidenclosure to said hot, moist air mixture for inhalation by the user, asdroplets having sized in the range of 2-20 μm.